The Global Positioning System (GPS) and its extensions in the Global Navigation Satellite Systems (GNSS) have become thoroughly pervasive in all parts of human society, worldwide. GPS and GNSS receivers are increasingly being integrated into devices, tools, and vehicles such as agricultural vehicles, construction equipment, and even in autonomously operated vehicles. In order to control the vehicles safely and with a necessary degree of precision, GNSS receivers are configured to utilize corrections data from various sources in conjunction with locally derived data. Implementations of these corrections systems include the Wide Area Augmentation System (WAAS), the Satellite-Based Augmentation System (SBAS), the Real-time Kinematic (RTK) technique, the Precise Point Positioning (PPP) technique, and the European Geostationary Navigation Overlay Service (EGNOS). Using data from these sources, a GNSS receiver can account for error sources such as atmospheric delay of clock signals, clock errors, ephemeris errors, etc. to derive a more precise position fix.
When first started up, a GNSS receiver using correction data initiates a process called “convergence” in which carrier phase ambiguities between the locally received signals and the correction data are resolved. Using the carrier phase observations, phase ambiguities are resolved to near constant values. A number of factors influence how fast convergence will take within a pre-defined level of precision. Such factors include, but are not limited to the number and geometry of visible satellites, the quality of the observations made by the GNSS receivers involved, sampling rate, availability of ionospheric corrections, etc. In a typical scenario, it takes approximately 30 minutes or more for a receiver to converge its locally received signals with the correction data it receives in a cold-start. Upon power up a previously converged GNSS receiver can leverage its previously known position to shorten the convergence process to a few minutes or less. However, if a previously converged receiver has been moved after shut-down, it will attempt to use its previous known position for convergence upon power up. This results in the convergence process taking longer than the approximately 30 minute period it would have taken if the GNSS receiver had performed a cold-start convergence.